This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7 119 from an application entitled Embedded Servo Writing Method and Apparatus for Hard Disk Drive earlier filed in the Korean Industrial Property Office on Mar. 6, 1997, and there duly assigned Ser. No. 97-7359 by that Office.
1. Technical Field
The present invention relates to a hard disk drive, and more particularly to a method and apparatus for writing a servo signal for controlling the position of a head on a disk during the manufacture of a hard disk drive.
2. Related Art
In general, a hard disk drive(hereinbelow, referred to as HDD) widely used as an auxiliary memory device in a computer system is a disk driving/recording apparatus for magnetically recording the data received from an external device(e.g., a host computer) onto a rotating disk (i.e., a magnetic recording medium) or reading the data recorded on the disk by using a magnetic head. The HDD enables high speed access to a large amount of data. Such data are typically stored within sectors on radially concentric tracks located across the disk. The data stored on the tracks are read or written by access of the data by the magnetic head. The magnetic head moves over the tracks across the disk radially under the control of a head position servo mechanism so that it can be positioned selectively over any one selected track among several tracks. In order to selectively position the head over the specific track, a present position of the head associated with each of tracks should be determined. Servo information indicative of the present position of the head relating to each of tracks is provided by using a specific servo pattern read from a magnetic disk by a head. The servo pattern, which is detected by the head during the access of data on the magnetic disk, is used as track position information. The method of writing such servo information on a disk basically comprises a dedicated servo method and an embedded servo method. For the dedicated servo method, the servo information is written on an entire surface of any one disk of a plurality of tracks, and is then read by a special servo head. As a result, the use of the read servo information controls the position of the heads over the surface of other disks. For the embedded servo method, servo information and data are alternately positioned on each track of an entire surface of each of a plurality of disks.
As will be explained in more detail below, the embedded servo method of writing servo information during the manufacture of a HDD has a problem in that high-priced equipment, such as laser equipment, is required to control the driver which is linked to an actuator of the HDD and to provide driving power. Furthermore, whenever HDD manufacturers attempt to increase the density (tracks per inch) of the HDD in order to achieve a high capacity HDD, they are compelled to produce a new servo writer, and this increases production cost accordingly.
Therefore, there is a need for the development of a method of writing servo information on a magnetic disk by directly driving an actuator of an HDD without the use of a mechanical device of a servo writer by means of control of expensive equipment, such as a laser. That is to say, there is a need to develop a method of writing servo information on a magnetic disk such that high-priced equipment, such as laser equipment, is not required to control the driver linked to the actuator of an HDD and to provide driving power.
The following patents are considered to be representative of the prior art relative to the invention disclosed therein, but are burdened by the disadvantages discussed herein:
U.S. Pat. No. 5,715,119 to Williams et al. discloses a Rotating Crash Stop Assembly For Hard Disk Drives in Which a Crash Stop Is Used For an Actuator Arm For a Hard Disk Drive; U.S. Pat. No. 5,687,038 to Sugawara et al. discloses a Servo Method and Device for Controlling Head Position for a Hard Disk Drive; U.S. Pat. No. 5,677,609 to Khan et al. an Intelligent Servomechanism Controller for Controlling the Movement and Positioning of a Servo Mechanism for the Read/write Heads of a Hard Disk; U.S. Pat. No. 5,616,869 to Valent an Actuator Torque Non-Linearity Compensation Technique for Hard Disk Drives; U.S. Pat. No. 5,602,693 to Brunnett et al. a Method and Apparatus for Positioning a Plurality of Heads Traversing Multiple Disks in a Disk Drive System; U.S. Pat. No. 5,570,247 to Brown et al. discloses a Self Servo Writing File and Method for Writing Servo Patterns in a Direct Access Storage Device; U.S. Pat. No. 5,455,726 to Liu discloses a Versatile Head Positioner Stop Which Bidirectionally Limits Movement of a Head Positioning Device in a Disk Drive System; U.S. Pat. No. 5,355,260 to Mikada discloses a Servo System for a Hard Disk Drive in Which a Malfunction Detection Circuit Monitors a Period of a Sync Signal Contained in a Servo Data; U.S. Pat. No. 5,325,349 to Taniguchi discloses a Hard Disk Drive and a Servo Signal Writing Apparatus; U.S. Pat. No. 5,262,907 to Duffy et al. discloses a Hard Disk Drive with Improved Servo System; U.S. Pat. No. 5,255,136 to Machado et al. discloses a High Capacity Submicro-Winchester Fixed Disk Drive; U.S. Pat. No. 5,241,430 to Janz discloses a Method and Apparatus for Alternatively Reading or Writing Data to a Servo Surface of a Hard Disk Drive; U.S. Pat. No. 5,168,398 to Kanda et al. discloses a Head Positioning Control Apparatus for a Data Storage Device; U.S. Pat. No. 5,164,863 to Janz discloses a Method for Writing Servo Patterns to a Disk of a Hard Disk Drive; U.S. Pat. No. 4,879,617 to Sampietro et al. discloses an Actuator Assembly for a Hard Disk Drive; U.S. Pat. No. 4,796,131 to Chang discloses a Winchester or Hard Disk Drive with a Head Positioner Provided with a Bidirectional Preloaded Stop; U.S. Pat. No. 4,766,508 to Mathewson discloses the Control of Head Position in Accordance with Prerecorded Sets of Burst Data; U.S. Pat. No. 4,757,406 to Stewart et al. discloses a High Capacity Disk Drive and Related Method for Generating and Protecting Hard Sector Pulses Using the Read/Write Heads of a Disk Drive; and U.S. Pat. No. 4,630,190 to Alaimo et al. discloses a Servo Control Apparatus for Controlling a Servo Means That Positions a Recording Head over a Storage Medium. 
It is, therefore, an object of the present invention to provide a method and apparatus for writing servo information on a magnetic disk by directly driving an actuator of an HDD without using a mechanical device of a servo writer by means of the control of a laser.
This and other objects of the present invention have been attained by providing a method of writing servo information on the surface of a plurality of disks in a HDD, comprising the steps of:
(a) positioning each of a plurality of heads over an outermost circumferential track disposed on the surface of corresponding disks in such a manner that the actuator, including a plurality of heads in the HDD, contacts an outer crash stop based on a control command for writing servo information;
(b) causing each of the plurality of heads to write corresponding head position identifying information on a first half track area of the outermost circumferential track based on the control command for writing servo information;
(c) moving each of the plurality of heads inwardly by {fraction (1/2+L )} track across the disk so that each head can be positioned over a second half track area of the outermost circumferential track area by using the written corresponding head position identifying information as a position control value;
(d) causing each of a plurality of said heads to write corresponding head position identifying information on the second half track area of the outermost circumferential track;
(e) sequentially moving each of the plurality of heads inwardly by {fraction (1/2+L )} track across the disk toward the next track in the same manner as the step (c);
(f) causing each of the plurality of heads to write a plurality of head position identifying information on the disk in the same manner as in step (d), thereby writing servo information on the all tracks of said surfaces of said disks.